Process and apparatus for recovering barium sulphate from barytes



M. J. RENTSCHLER l,959,305 PROCESS AND APPARATUS FOR RECOVERING BARIHUMSULPHATE FROM BARYTES May l5, 1934.

5 SheetS-Sheet l v -Filed July, 1932 May 15, 1934- M. J. ENTSCHLER I v1,959,305

ROCESS AND APPARATUS FOR RECOVERING BARIUM SULPHATE FROM BARYTES FiledJuly 8, 193'2' -5 sheets-sheet i ll IMI i May 15, .1934- M. J.RENTscHLx-:R 1,959,305

PROCESS AND APPARATUS FOR. RECOVERING BARIUM SULPHATE FROM BARYTES FiledJlily 8, 1932 v 3 ,Sheets-Sheet 5 Patented May 15, v 1934 f UNITEDSTATES PATENT OFFICE PROCESS AND- APPARATUS FOR RECOVER*- ING BARIUMSULPHATE FROM BARYTES Mahlon J. Rentschler, Willoughby, Ohio, assignorof one-half to William R. Jeavons, Cleveland Heights, Ohio ApplicationJuly 8, 1932, Serial No. 621,376

12 Claims. (Cl. .2S-122) The sulphide (BaS) is then treated with sodiumsulphate (Na2SO4)) which produces barium sulphate according. tov theequation It is apparent that in this process the barium sulphatemolecule finally secured is a synthetic product and not one occurring innature. Furthermore, in practice the products actually obtained are notentirely those indicated by the foregoing equation, numerous othercompounds being formed in greater or lesser amounts as well as tlioseindicated. Some of these other compounds are undesirable and difficultto eliminate in the finished product.

I have discovered a method of obtaining the natural (non-synthetic)barium sulphate from barytes in a simple, direct and inexpensive mannerwhich results in barium sulphate of a smaller grain size tllan that madeby the conventional process while being substantially free from theimpurities contained in barytes.

I` am also able by a variation hereinafter described to control thegrain size whereby to produce the greatly reduced size or a size evenlarger than now commercially available as well as various sizes inbetween.

The principal object of my invention is to provide a method of producinga better quality of bariumsulphate at a lower cost than has heretoforebeen possible. A further object is to provide a process in which it isnot necessary to reduce the ore to powdered form and in which it is notva transverse section taken on the line 3 3 of Fig. 1; Fig. 4 isa'fragmentary section on the line 4 4 of Fig. 1; and Fig. 5 is afragmentary vertical section showing a modified form of mechanism forfeeding purifying material.

The apparatus disclosed in the drawings will rst be described afterwhich my improved method will be described in connection with theoperation of the apparatus.

The numeral 10 indicates generally a receptacle @5 I of suchconstruction that it is adapted to contain a lake 11 ofmoltenvsodium'chloride or other alkali metal chloride. 'Ihis receptaclemay take V the form of a metallic outer wall 12 having a refractorylining 13 composed of material which 70 will not be attacked by themolten salt solution. The receptacle 10 is tiltablymountedas for exampleon supports 14 about a pivot bar 15. Suitable bearings 16 may be securedto the bottom of the furnace in any suitable manner. Any means 76 may beemployed for maintaining the furnace normally in the position shown inFig. 1 while allowing it to assume a position in which the bottom liesalong the line AB. This may take the form of an upright stop 17 havingmounted 80 thereon a winding drum 18 upon which is adapted to be wound acable 19 connected as at 20 to the bottom of the furnace. .The pivot bar15 is mountf ed slightly to the left of the center of gravity of thefurnace whereby a slight holding force is necessary to prevent thefurnace from normally assuming a position along the line A-B. A veryslight force will then be able to hold itin normal position as shown. Itis to be understood that any other equivalent mechanism may be employedfor obtaining the same results. At the left hand end of the furnace asseen in Fig. 1 an upward inclination is given to the floor as indicatedat 21 for facilitating the removal of sediment through the door 22.Doors 23, 24 95 and 25 and slopes 23a, 24a-and 25a are also provided forallowing access to compartments formed by the partitions 26, 27 and 28.The partition 26 is provided with an overflow opening or notch 29located adjacent one end thereof. The par- 100 tition 27 is providedwith a passage 30 adjacent the bottom for establishing communication'between compartments and is located adjacent the opposite end from theoverflow opening 29. The partition 28 has an overflow opening 31 located105 at the saine end as 29. Liquid passing the opening 29 must sink tothe bottom, pass through opening 30 and again rise to the top andoverflow 31 into the last compartment C. Inasmuch as all the materialpassing through theopening 30 110 In practice this may amount to aboutone ounce per ton of barytes'. The gaseous fuel in the form of a mixtureof finely divided` oil particles and air or natural or artificial gasfor heating the interior of the furnace to a temperature above themelting point of sodium-chloride or other alkali metal chloride employedmay be 'introduced through one or more pipes 32. These pipes may be madeof heat resistant material or may terminate outside the receptacleallowing an opening in the wall thereof to constitute the termination ofthe fuel supply passages.

A combined compressed air and screw conveyor mechanism indicatedgenerally by the reference character D is provided for distributivelyfeeding the crushed ore and additional salt to the surface of the lake11. Ihis mechanism comprises a hopper 33 having a screw conveyor 34working in a passage at the bottomthereof. The conveyor 34 may be drivenby any suitable prime mover and will feed a predetermined quantity ofthe material in the hopper to the passage 35 to which is connected asource 36 of compressed air. The material in the hopper 33 will uponreaching the passage 35 come within the influence of the compressed airjet and be scattered over the surface of the lake 11 as indicated in thedrawings. A baiiie 37 isprovided for preventing any of the material frompassing beyond the lake 11 and falling into any of the succeedingcompartments.

g Positioned above the compartment C adjacent the overow opening ornotch '31 is the outlet 33 of a feeding means E adapted to supply adecolorizing or purifying material for decolorizing or removing suchimpurities contained in barytes as are soluble in molten sodium chlorideo r other salt employed. This outlet opening is so positioned that thepurifying or decolorizing material is dropped into the compartment O ata point where the material is agitated by the cascading of the solutionthrough the passage 31 for the purpose of bringing about mixing in aminimum time. In Fig. 5 I have shown a modified form of feeding meansindicated generally by the numeral E' which is .simply an openingthrough which lumps or aggregations of the decolorizing and purifyingmaterial may be introduced. The outlet spout 39 is positioned at such adistance from the inlet opening 38 that the solution will be drawn oi assoon as the purifying or decolorizing material has thoroughly mixedtherewith.

This is an important feature of my invention inasmuch as the purifyingand decolorizing effects are greatly increased by cooling the materialas soon after the introduction of the purifying or decolorizing agent aswill allow thorough mixing. In the drawings I have shown only one methodof cooling the liquid drawn from the compartment C, namely, dischargingit into water in the tank li'.

This method at the same time accomplishes cooling promptly after mixingof'the purifying and decolorizing agent and arrests crystal growthalmost at its inception whereby to secure the extremely fine grain size.If it is desired to secure a large grain size the prompt cooling maybeaccomplished by a method which will not arrest crystal growth.Forexample, the liquid from the compartment C may be dropped upon arapidly vrevolving paddle wheel whereby it is formed into a spray forcooling and thereafter may be discharged into water, the time elapsingbetween cooling and discharging into water servis taken from the bottom,any floating insoluble material will `remain in the second compartment.

ing to control the amount ofV crystal growth and -therefore the grainsize.` I may also enlarge the grain size of the line powder' secured byimmediately discharging into water and this may be accomplished byboiling such material in hydrochloric acid. The time of boiling willdetermine the crystal size. I may in this manner produce monoclinicbarium sulphate crystals large enough to be seen with the naked eye. Thefeeding means E may be of any desired construction, that shownconsisting `of a hopper 40 and reciprocable ejector 41 adapted to feedthe material through the opening 38 at a predeterminedv rate. It isdesirable that the feeding unit should be so constructed as not topermit furnace gases to pass out therethrough. A pump 42 is provided fordrawing out the barium sulphate in. the receptacle F along with some ofthe liquid and delivering to filter presses of usual constructionlnfnoty shown). I may, of course, provide means for supplying additional waterto the tank F and for agitating the water in such tank, according tocommon practice in fritting molten liquids.

I provide a stack S normally communicating with the interior of thefurnace by an opening s. The stack may be supported independently of thetiltable furnace as indicated in Fig. 3.

In carrying out my improved process the vbarytes ore is washed, driedand crushed preferably to about 4-mesh (size to pass screen of V4 meshesto the inch). It is of great importance that the ,material introducedinto the lake 11 be dried since steam formed in the lake would stir upsediment' and prevent proper separation of liquid and solid. It is notessential in my'process as in the conventional oneA described that theore should be reduced to powdered form; and this is an importantadvantage in my process, resulting as it does in a considerable savingin the cost of preparing the ore. After crushing the ore is crudelymixed with approximately twice its weight of dry sodium chloride orother alkali metal chloride and the mixture, containing substantially nowater, is fed continuously by the feeding means D into the furnace whereit falls upon the lake 11 of the molten salt. The temperature of thelake 11 is preferably well above the melting point of the salt (776 C.for, NaCl) whereby the salt particles introduced with the ore are meltedsubstantially instantaneously. The granules or small lumps of ore aredissolved in a very short time and sink below the surface almostimmediately, forming no local aggregations in the lake. 1t is aquiteimportant that the Vlake 11 should not be agitated to any great extenteither by the introduction of material or any other cause and that theaverage, over all tem- .perature should be below the point ofVolatilization of the salt employed. The compressed air current whichcarries the charge into the furnace should not interfere with the fuelfeed. This temperature will preferably be about 2100 F.` for sodiumchloride. By maintaining the temperaturev at this high level andscattering the crushed ore and granular salt-upon the-surface of thelake 11 the formation of crusts of salt on the surface of the lake isprevented and thorough mixing of the ore without considerable agitation-of the lake 11 is facilitated. The barium sulphate contained in the oretogether with a limited loating insoluble material.

may be accomplished by tipping down to the position of the line A-Bwhich will'cause most of the liquid to flow into the right hand endleaving the sediment accessible for removal by a furnace hoe or similarinstrument. The solution comprising fused salt having dissolved thereinbarium sulphate and a limited number of impurities flows through theopening 29 and back and forth through the intervening compartments forvallowing further and complete settling of insoluble material afterwhich it cascades through the opening 31 into the compartment C. Thematerial passes from the lake 11 over the partition 26 allowing thesettling of heavy particles in the first compartment after which itpasses under partition 27 whereby to effect skimming of any When theliquid flows through the passage 31 to the much lower level in thecompartment C it agitates the contents of that compartment wherebymaterial from the hopper 40 is quickly and thoroughly mixed therewith. v

The decolorizing or purifying material introduced through the opening 28from the hopper 40 may be any substance which will effect the desiredresults, and for many purposes its use is optional.

After the solution has been discharged into .water in the tank F thesodium chloride dissolves out leaving insoluble barium sulphate in saltwater which may be ltered olf and washed out leaving substantially purebarium sulphate.

I have found that by the use of this process I am able to secure bariumsulphate of a high degree of purity and, if desired, in a very nelydivided state, the resulting material having an apparent densitysubstantially one-half that of the present commercial product, and beingin a state of division fine enough to pass 99.96% through a screen of325 mesh. Microscopic analysis shows that 30 particles in a row wouldpass laterally through the opening in a 325 mesh screen.

The resulting product after having been discharged into water andfiltered is strictly neutral, a feature which is of considerableadvantage in many uses of the product.

The term granular as herein applied to crushed barytes is not to beunderstood in a limiting sense, but as describing the size of thecrushed orewhich canV be successfully and emciently used within thisperiod of the process described. The size to which the ore is crushedmay be larger or smaller than might be understood conventionally by theterm granular so long as it is suflciently small that it will bedissolved or substantially dissolved at a point near the top of thelake. It is preferred that the bulk of the ore should be about the sizewhich would be conventionally understood by the word granular, that is,about the size of common cereal grains but a portion may be finer and aportion coarser. There should however be no large lumps and but fewlumps vwhich might be considered too coarse to beconsidered granular.These tolerances are to be understood as implied by the. word granularor words of similar import. v

While I have set forth in considerable detail the manner of practicingmy invention and' construction of the apparatus employed I Wish itunderstood that I am not limited to details but only in accordance withthe spirit and scope of the appended claims.

Having thus described my invention, what I claim is:

1. In a furnace of thec aracter described, a receptacle adapted to contaa lake of molten material, means for supplying radiant heat to thesurface of said lake, and separate means independent of said rst meansfor distributively feeding granular material to said lake, said lastmeans comprising a container for containing the material to be fed in,means for feeding such granular material from said container at apredetermined rate, and means for distributing the material so fed uponthe surface of said lake.

2. A furnace of the character described comprising a receptacularportion adapted to contain a lake of molten material, cover meansforming a substantial enclosure for said lake and a substantial spacethereabcve, one'or more fluid fuel burners spaced above the lake forheating the same by radiation, and means separate from and independentof said burners for thinly scattering granular material upon thesurfaceof said lake.

3. A furnace of the character described comprising a receptacularportion adapted to contain a lake of molten material, cover meansforming a substantial enclosure for said lake and a substantial spacethereabcve, one or more fluid fuel burners spaced above the lake forheating the same by radiation, and means for thinly scattering granularmaterial upon the surface .of said lake, said means comprising a pipefor compressed gas delivering to the interior of said enclosure at apoint vertically spaced from said burners, and means for feeding suchgranular material to said compressed gas pipe.

4. A furnace of the character described comprising a receptacularportion adapted to contain a lake of moltenmaterial, cover means forminga substantial enclosure f or said lake and a substantial spacethereabcve, one or more fluid fuel burners spaced above the lake forheating the same by radiation, and means for thinly scattering granularmaterial upon the surface of said lake, said means comprising a pipe forcompressed gas delivering to the interior of' said enclosure at asubstantial distance above said .burners whereby not to interfere withthe operation thereof or cause incomplete combustion of the fuel, andmeans for feeding such granular material to said compressed gas pipe.

5. lIhe process which comprises heating by radition a. lake of barytesand molten alkalimetal salt, maintaining said lake placid, scatteringsubstantially uniformly upon a charge receiving portion of said lakedrycrushed barytes and dry granular alkali metal salt,l allowing thelinsoluble material to settle, and decanting the solution.

6. In the continuous process of recovering barium sulphate from barytesby dissolving the barium sulphate constituent in a molten alkali metalsalt, the step of continuously charging the ore into a lake containingthe molten salt, said ore being in granular form and the entire chargebeing scattered upon the surface of said lake.

7.' In the continuous process of recovering barium sulphate from barytesby dissolving the barium sulphate constituent in a molten alkali metalsalt, the step of continuously charging a mixture of the ore and thesalt into a lake containing the molten salt, said ore and salt being ingranular form and the entire charge being scattered upon the surface ofsaid lake.

8. In the continuous process of recovering lll@ lll@

barium sulphate from'barytes by dissolving the barium sulphateconstituent in a molten alkali metal salt, the step of continuouslycharging the ore into a lake containing the molten salt, said` ore beingin granular form and the entire charge being scattered substantiallyuniformly upon a charge receiving portion of the surface of said lake.

9. 'In the continuous process of recovering barium sulphate from barytesby dissolving the barium sulphate constituent in a molten alkali metalsalt, the step of continuously charging a mixture of the ore and thesalt into a lake `containing the molten salt, said ore and salt being ingranular form and the entire charge being scattered substantiallyuniformly upon a charge receiving portion of the surface of said lake.V

10. In the continuous process of recovering barium sulphate from barytesby dissolving the barium sulphate constituent in a molten alkali metalsalt, the step of continuously charging the dry ore into a lakecontaining the molten salt, said vore being in granular form and theentire charge being scattered upon the surface of said lake.

11.In the barium sulphate from baryts by dissolving the barium sulphateconstituent in a molten alkali metal salt, the step of continuouslycharging a dry mixture of the ore and the salt into a lake containingthe `molten salt, said ore and salt being in granular form and theentire charge being scattered upon the surface of said lake.

12. In the process of recovering barium sulphate from barytes bydissolving the barium sulphate constituent thereof in molten alkalimetal salt, the step of introducing the crushed barytes continuousprocess of recovering by continuously scattering the same during a Aconsiderable period of time upon the surface of a lake containing themolten salt.

MAHLON J. RENTSCHLER.

